The present invention is a surgical device. More particularly, it is an endolumenal prosthesis which is adapted for use in bifurcated regions of body lumens. Still more particularly, it is an endovascular stent which is adapted to provide radial support to a main lumen of an endolumenal bifurcation and which includes a dilator and access device which are preloaded within a preselected side port along the endolumenal prosthesis prior to delivery of the endolumenal prosthesis to the bifurcation region in order to facilitate delivery of a second endolumenal prosthesis through the side port and into a side branch extending from the main lumen at the bifurcation region.
Conventional Stents
A wide range of medical treatments have been previously developed using xe2x80x9cendolumenal prostheses,xe2x80x9d which terms are herein intended to mean medical devices which are adapted for temporary or permanent implantation within a body lumen. Examples of lumens in which endolumenal prostheses may be implanted include, without limitation: arteries, such as for example those located within the coronary, mesentery, peripheral, or cerebral vasculature; veins; gastrointestinal tract; and fallopian tubes. Various different types of endolumenal prosthesis have also been developed, each providing a uniquely beneficial structure to modify the mechanics of the targeted lumenal wall. For example, various grafts, stents, and combination stent-graft prostheses have been previously disclosed for implantation within body lumen. More specifically regarding stents or stent-grafts, various designs of these prostheses have been previously disclosed for providing artificial radial support to the wall tissue which forms the various lumens within the body, and usually more specifically within the blood vessels of the body.
One more frequently disclosed xe2x80x9cstentingxe2x80x9d treatment beneficially provides radial support to coronary, peripheral, mesentery or cerebral arteries in order to prevent abrupt reclosure subsequent to recanalization of stenosed vessels, such as by balloon angioplasty or atherectomy (mechanical dilation of stenosed vessel by radial balloon expansion or direct removal of stenotic plaque, respectively). In general, the angioplasty or atherectomy-type recanalization methods reestablish flow to reperfuse tissues downstream of an initial stenosis. Subsequent to such recanalization, however, the dilated lumen of the stenosis site may reocclude, such as by abrupt reclosure (usually due to acute thrombosis or dissected vessel wall flaps transecting the vessel lumen), restenosis (generally considered as a longer term xe2x80x9cscarringxe2x80x9d-type response to wall injury during recanalization procedures), or spasm (generally considered a response to overdilatation of a vessel and in some aspects may be a form of abrupt reclosure). The implantation of stents to mechanically support the vessel walls at such stenosis sites, either during balloon angioplasty or subsequent to recanalization, is believed to deter the reocclusion of such recanalized vessels which may otherwise occur due to one or more of these phenomena. Various categories of stents have therefore arisen for the primary purpose of providing endolumenal radial support primarily within arteries adjunctively to recanalization.
One criteria by which various stent designs may be generally categorized draws from the structural design which forms a particular stent""s tubular wall. Various xe2x80x9ctubular wallxe2x80x9d types of stents according to this criteria include, without limitation: wire mesh stents; coiled stents; tubular slotted stents; and integrated ring stents. In general, each of these xe2x80x9ctubular wallxe2x80x9d categories of stents includes a network of integrated support members which combine to form a tubular stent wall that defines a longitudinal passageway. The structural integrity of the integrated support members provides radial rigidity against physiological collapse forces at the vessel wall, whereas the longitudinal passageway through the prosthesis allows for perfused flow through the stented region.
Another criteria by which various stent xe2x80x9ctypesxe2x80x9d may be categorized relates to the delivery method by which a particular stent is adapted for implantation within a lumen or vessel. In general, stents are delivered in a radially collapsed condition to the stenting site via known percutaneous translumenal procedures. Once positioned at the stenting site, the stent is adjusted to a radially expanded condition which is adapted to radially engage the interior surface of the wall tissue which defines the lumen, such as a vessel wall in an arterial stenting procedure. According to this generally applicable delivery mode, various stent categories which may be stratified by more particular delivery methods include, without limitation: xe2x80x9cself expandingxe2x80x9d stents, which generally expand under their own force once delivered to the desired stenting site; and xe2x80x9cballoon expandablexe2x80x9d stents, which generally expand under mechanical strain from an inflating balloon at the stenting site.
One specific example, within the previously disclosed xe2x80x9cself-expandingxe2x80x9d stenst is adjustable from the radially collapsed condition to the radially expanded condition by removing a radial constraining member once delivered to the stenting site. This type of self-expanding stent is adapted to recover from an elastically deformed state, when radially confined by the constraining member in the radially collapsed condition, to a resting or recovered state in the radially expanded condition, when radially unconstrained. Further detailed examples of known constraining members for use in delivery systems for such known xe2x80x9cself-expandingxe2x80x9d stents include either radially confining sheaths or releasable tethers which are releasably coupled to the stent wall when in the radially collapsed condition. Another more specific example of a previously disclosed xe2x80x9cself-expandingxe2x80x9d stent is adjustable from the radially collapsed condition to the radially expanded condition by heating the stent once delivered to the stenting site, thereby inducing a heat-memory recovery of the stent to the radially expanded condition.
Further to the previously disclosed xe2x80x9cballoon expandablexe2x80x9d stent variations, known stents according to this type are generally crimped or otherwise held in the radially collapsed condition over an exterior surface of an expandable balloon and are adjusted to the radially expanded condition by inflating the balloon. Further detail of previously known xe2x80x9cballoon expandablexe2x80x9d stent designs includes those which are provided xe2x80x9cpre-loadedxe2x80x9d onto a balloon catheter, and also those which may be provided separately to a physician user who may crimp the stent onto a balloon immediately prior to delivery in vivo.
Further more specific examples of stents according to the various xe2x80x9ctubular wallxe2x80x9d and xe2x80x9cdelivery methodxe2x80x9d categories just summarized above are disclosed variously throughout the following references: U.S. Pat. No. 4,580,568 to Gianturco; U.S. Pat. No. 4,733,665 to Palmaz; U.S. Pat. No. 4,739,762 to Palmaz; U.S. Pat. No. 4,776,337 to Palmaz; U.S. Pat. No. 4,830,003 to Wolff et al.; U.S. Pat. No. 4,913,141 to Hillstead; U.S. Pat. No. 4,969,458 to Wiktor; U.S. Pat. No. 5,019,090 to Pinchuk; and in U.S. Pat. No. 5,292,331 to Boneau. The disclosures of these references are herein incorporated by their entirety by reference thereto.
Conventional Bifurcation Stenting Techniques
Stenoses within bifurcation regions of lumens, more particularly of arterial lumens, have long presented a particular challenge to conventional recanalization techniques, and more particularly to conventional stenting techniques. For example, adjunctively to implanting a stent within a main vessel, which includes a side-branch vessel arising from the main vessel wall along the implanted stent""s length, additional stenting of the side-branch vessel may also be required in order to maintain patency of that vessel. The various clinical indications or concerns which are believed to give rise to the desirability of such bifurcation stenting include: mechanical closure of an acutely bifurcating side-branch due to angioplasty of the main vessel or implantation of the main vessel stent; additional stenotic disease in the side-branch vessel; and flow reduction and poor hemodynamics into the side-branch from the main vessel due to the occlusive presence of the main vessel stents structure in the entrance zone to the side branch. However, it is further believed that conventional stent designs present significant mechanical and procedural challenges to successful stenting of both the main and side-branch vessels at bifurcations of body lumens, and particularly within arterial bifurcations.
One conventional bifurcation stenting technique which has been previously disclosed includes first stenting the side-branch and then the main vessel. However, several challenges and incumbent risks related to this alternative method have been disclosed. For example, angle variations or limited angiographic visualization at the side-branch take-off may prevent accurate placement of the first stent exactly in the ostium of the side-branch, thereby resulting in a sub-optimal result in the ostium. Furthermore, placement of the first stent too far proximally at the take-off may occlude and prevent subsequent stenting of the main vessel.
Another conventional bifurcation stenting technique which has been previously disclosed includes first stenting the main vessel and then advancing a second stent through the wall of the main vessel stent and into the side-branch where it is deployed. However, this technique is also generally believed to be challenging due to the main vessel stent""s tubular wall which occludes or xe2x80x9cjailsxe2x80x9d the side-branch from access with the side-branch stent.
According to the challenges of conventional bifurcation stenting techniques just summarized, several modified stent deployment procedures have therefore been developed in attempt to safely and accurately implant conventional stents into both the main vessel and also the side-branch vessel at bifurcation regions of body lumens. In addition, particular stent designs have also been disclosed which are specifically intended for implantation within a bifurcation region and which are alleged to enhance the delivery of a second side branch stent using otherwise conventional techniques.
Modern Bifurcation Stenting Techniques using Conventional Stents
Several modern bifurcation stenting techniques which modify the use of conventional stents in bifurcation stenting procedures have been disclosed by David P. Foley et al. in xe2x80x9cBifurcation Lesion Stenting,xe2x80x9d The Thoraxcentre Journal, Volume 8, Number 4 (December 1996), and include the xe2x80x9cMonoclonal Antibodyxe2x80x9d approach; the xe2x80x9cCulotte techniquexe2x80x9d; and the xe2x80x9cInverted Yxe2x80x9d technique. The disclosure of this reference is herein incorporated in its entirety by reference thereto.
According to the xe2x80x9cmonoclonal antibodyxe2x80x9d approach disclosed in Foley et al., two guidewires are each delivered through an 8 French guiding catheter and into each of two branches at a bifurcation region, respectively, preferably using a 0.010xe2x80x3 guidewire in the side-branch at the bifurcation. Either the bifurcation lesion is dilated in each of the branch vessels separately, or in a xe2x80x9ckissingxe2x80x9d balloon technique wherein two balloons are simultaneously inflated in the branch vessels, usually with some balloon overlap in the proximal main vessel. Then, a stent of appropriate length is deployed into the main vessel, thereby xe2x80x9cjailingxe2x80x9d the 0.010xe2x80x3 wire in the side-branch vessel. Using the jailed 0.010xe2x80x3 wire as a radiopaque landmark, an additional wire, also preferably 0.010xe2x80x3 diameter, is then placed into the side branch through a gap between the support member of the main vessel stent""s wall, after which the first xe2x80x9cjailedxe2x80x9d 0.010xe2x80x3 guidewire is removed. A dilatation balloon is then advanced over the second 0.010xe2x80x3 wire through the gap between the main vessel stent""s support members, wherein the balloon is then inflated to dilate open the gap. A side-branch stent is then advanced through the dilated open gap and is deployed into the side-branch.
The xe2x80x9cCulottexe2x80x9d technique disclosed in Foley et al. generally includes the following method. The first of two specific xe2x80x9cFreedomxe2x80x9d stents is implanted within the main vessel, including a first branch lumen of a bifurcation. A wire is then advanced through the side of the first stent and into the distal branch of the main vessel. The distal end portion of a second xe2x80x9cFreedomxe2x80x9d stent is then advanced over the wire and through the side of the first stent and into the second side branch lumen of the bifurcation, leaving the proximal end portio of the second xe2x80x9cFreedomxe2x80x9d stent within the proximal main vessel. According to this positioning, the second stent is implanted within both the second branch lumen and also in overlapping arrangement with the first stent in the main vessel. However, a risk of dissecting the side-branch is present in this technique because the side branch stent is oversized to that branch in order to properly engage the proximal main vessel.
According to the xe2x80x9cInverted Yxe2x80x9d technique disclosed in Foley et al. and previously described by Antonio Colombo, two stents are each placed within first and second side branch lumens at a bifurcation region extending distally from proximal, main vessel lumen. Two guidewires are left in place within and through the implanted side branch stents. A third stent is then crimped onto two adjacent balloons which are adapted to track the indwelling guidewires to the proximal, main vessel lumen of the bifurcation region wherein the third stent is then implanted by expanding the two balloons adjacent to the first and second side branch stents. Further to the xe2x80x9cInverted Yxe2x80x9d techniques just described, accurate positioning of each of three stents relative to the other stents is required, which may further require intracoronary ultrasound, and wire crossing particularly between delivery of the first two stents and the third stent may be a significant obstacle which may require a xe2x80x9ctest runxe2x80x9d with the two balloon catheters prior to crimping the third stent thereover. Therefore, Foley et al. further discloses a modified variation of the xe2x80x9cInverted Yxe2x80x9d technique, wherein the three stents described are together pre-loaded onto two long balloons such that the entire xe2x80x9cbifurcation stentxe2x80x9d may be placed in one manoeuvre. However, this modified vartiation is believed to by more bulky and rigid than the initial xe2x80x9cInverted Yxe2x80x9d technique and may require very good predilatation and ideally a fairly proximally located and easy to reach bifurcation in reasonably large vessels.
Further disclosure of conventional stenting techniques is also provided by Freed, M. D., et al. in xe2x80x9cThe New Manual of Interventional Cardiology,xe2x80x9d Chapter 10, pp 238-243, Physicians"" Press, 1996. The disclosure of this reference is herein incorporated in its entirety by reference thereto.
Modern xe2x80x9cBifurcation Stentsxe2x80x9d
Particular stent designs have also been disclosed which are specifically intended for use within arterial bifurcation regions. More particularly, two stent designs which appear to be specifically designed for use within arterial bifurcation regions, respectively called the xe2x80x9cSITOstentRSxe2x80x9d and the xe2x80x9cJOStentRBxe2x80x9d, have been previously disclosed by xe2x80x9cPENTACHI-SITOmed SrLxe2x80x9d corporation located in Milan, Italy. In general, each of these particular stents includes a region along the stent tubular wall which has larger spaces or xe2x80x9cside portsxe2x80x9d between support members than are provided at other regions along the stent tubular wall.
More particularly regarding the previously disclosed xe2x80x9cSITOStentRS,xe2x80x9d the widely spaced side port region appears to be positioned along a midportion of the stent tubular body, wherein it is bordered on either side by a more tightly structured tubular wall. The xe2x80x9cSITOStentRSxe2x80x9d further appears to be adapted for positioning along a main artery such that the widely spaced side port region along its midportion is aligned with a side branch extending from the main artery.
In contrast, the previously disclosed xe2x80x9cJOStentRBxe2x80x9d appears to provide the widely spaced side port region along one end portion, which appears to be the intended proximal end portion, of the stent tubular wall. The xe2x80x9cJOStentRBxe2x80x9d further appears to be adapted for positioning within a bifurcation region such that a distal, tightly integrated support member portion is located within a first branch lumen extending from the bifurcation zone, and such that the proximal, widely spaced side port region extends across the entrance zone to a second branch lumen extending from the bifurcation region and is further positioned only partially within the more proximal main or common artery. It further appears from the prior disclosure of the xe2x80x9cJOStentRBxe2x80x9d that the alignment of the relatively widely spaced side port region with the entrance zone of the second side branch artery is adapted to facilitate delivery of a second stent, which may be a second xe2x80x9cJOStentRBxe2x80x9d, through one of those widely spaced side ports and into the second branch lumen for implantation adjacent to the bifurcation.
None of the cited references discloses an endolumenal prosthesis assembly with a tubular prosthesis body which is adapted for implantation within a bifurcation region of a body lumen such that a second prosthesis may be subsequently implanted within a side branch lumen extending from the bifurcation region along the length of the implanted tubular prosthesis body without the need to sub-select a side port along the tubular prosthesis body which is aligned with the side-branch and then deliver the second prosthesis through the sub-selected side port.
Nor do the cited references disclose an endolumenal prosthesis assembly with a tubular prosthesis body which is adapted for implantation within a main lumen of a bifurcation region of a body lumen, and wherein the prosthesis assembly is further adapted for preselecting a side port along the prosthesis body, prior to delivering the prosthesis body to a bifurcation region of a body lumen, which may then be aligned with one side branch lumen extending from the main lumen and through which a second prosthesis may be delivered and implanted within the side branch lumen.
Nor do the cited references disclose an endolumenal prosthesis assembly with a tubular prosthesis body which is adapted for implantation within a main lumen of a bifurcation region of a body lumen, wherein the prosthesis assembly further includes a dilator pre-engaged within and through a side port along the prosthesis body prior to implanting the prosthesis body within the main lumen, and which is further adapted such that the side port and dilator may be aligned with a side branch lumen extending from the main lumen subsequent to positioning the prosthesis body within the main lumen but prior to implanting the prosthesis body within the main lumen.
Nor do the cited references disclose an endolumenal prosthesis assembly with a tubular prosthesis body which is adapted for implantation within a main lumen of a bifurcation region of a body lumen, wherein the prosthesis assembly further includes an access device which is pre-engaged within and through a side port along the prosthesis body prior to implanting the prosthesis body within the main lumen, and wherein the prosthesis assembly is further adapted such that the side port and access device maybe aligned with a side branch lumen extending from the main lumen along the length of the prosthesis body subsequent to positioning the prosthesis body within the main lumen but prior to implanting the prosthesis body within the main lumen.
The present invention is an endolumenal prosthesis assembly which is adapted for engaging an interior surface of a body lumen wall at a bifurcation region of a body lumen, preferably within a main lumen of a bifurcation region in an arterial vascular tree. The assembly includes an expandable prosthesis therethrough which has an elongate prosthesis body with a proximal end portion, a distal end portion, a prosthesis passageway extending along the longitudinal length of the body, and a side port which is positioned along the body""s length and through which the prosthesis passageway communicates externally of the elongate prosthesis body. The expandable prosthesis is adjustable from a radially collapsed condition, wherein the elongate prosthesis body has a collapsed outer diameter, to a radially expanded condition, wherein the elongate prosthesis body has an expanded outer diameter which is larger than the collapsed outer diameter. The distal end portion of a delivery member is coupled to the expandable prosthesis in order to deliver the expandable prosthesis to the bifurcation region in a percutaneous translumenal procedure. The distal end portion of an expansion member is also removably engaged with the elongate prosthesis body and is adapted to adjust the expandable prosthesis from the radially collapsed condition to the radially expanded condition.
In one mode of the invention, the distal end portion of a dilator is engaged within the prosthesis passageway and also within the side port and is adjustable from a first dilator position, wherein the side port has an initial inner diameter, to a second dilator position, wherein the side port is dilated to an expanded inner diameter which is larger than the initial inner diameter.
In one aspect of this mode, the dilator""s distal end portion includes an expandable member which is engaged within the side port. The expandable member is adjustable from a radially collapsed condition, which characterizes the first dilator position, to an radially expanded condition, which characterizes the second dilator position. In a further variation of this aspect, the expandable member is an expandable balloon and is fluidly coupled to a dilator inflation lumen which is adapted to couple to a pressurizeable fluid source.
In another aspect of this mode, the dilator""s distal end portion includes a taper with a distally reducing outer diameter from a large outer diameter portion to a small outer diameter portion. In the first dilator position, the small outer diameter portion is engaged within the side port, and in the second dilator position the large outer diameter portion is engaged within the side port.
In yet another aspect of this mode, the expandable prosthesis is an endolumenal stent which is adapted to provide radial support to the body lumen wall when the expandable prosthesis is expanded from the radially collapsed condition to the radially expanded condition. The side port of the endolumenal stent aspect of the invention is formed by a gap between adjacent support members which form the stent""s tubular body. Further to this aspect, the stent may be self-expanding, in which case the expansion member is a radially confining sheath which is adjustable over the stent between a constraining position to a releasing position, or may be balloon expandable, in which case the expansion member is an expandable balloon.
In still a further aspect of this mode, a lateral expandable prosthesis is coupled at its proximal end portion to the elongate prosthesis body at a location adjacent to the side port. The lateral expandable prosthesis has a lateral elongate prosthesis body with a proximal end portion, a distal end portion, and a lateral prosthesis lumen extending between a proximal end port located along the proximal end portion of the lateral elongate prosthesis body and a distal end port located along the distal end portion of the lateral elongate prosthesis body. The lateral expandable prosthesis is also adjustable from a second radially collapsed condition, wherein the lateral elongate prosthesis body has a second collapsed outer diameter, to a second radially expanded condition, wherein the lateral elongate prosthesis body has a second expanded outer diameter. Further to this aspect, the dilator""s distal end portion is also engaged within the lateral prosthesis lumen such that when the dilator is adjusted from the first dilator position to the second dilator position the lateral expandable prosthesis is expanded from the second radially collapsed condition to the second radially expanded condition.
In another mode of the invention, the assembly includes an access device with a proximal end portion and a distal end portion. The distal end portion of the access device is engaged within the prosthesis passageway and also within the side port when the expandable prosthesis is in both the radially collapsed and radially expanded conditions. According to this mode, the expandable prosthesis may be positioned at the bifurcation region with the distal end portion of the expandable prosthesis located within the first branch lumen and with the side port aligned with the entrance zone to the second branch lumen such that the access device is adapted to provide percutaneous translumenal access to the second branch lumen.
In one aspect of this mode, the access device includes a guidewire which has a proximal end portion and a distal end portion. The guidewire""s distal end portion has a shaped, radiopaque tip region which is steerable by torquing the proximal end portion of the guidewire, and which is engaged within the prosthesis passageway and extends distally through the side port when the expandable prosthesis is in both the radially collapsed and the radially expanded conditions.
In another aspect of this mode, the access device includes a guidewire tracking member with a proximal end portion, a distal end portion which is engaged within the prosthesis passageway when the expandable prosthesis is in both the radially collapsed and the radially expanded conditions, and a guidewire lumen which is formed at least in part by the distal end portion of the guidewire tracking member. The guidewire lumen communicates externally of the guidewire tracking member through a distal guidewire port located along the distal end portion of the guidewire tracking member at or adjacent to the side port and also through a proximal guidewire port located along the guidewire tracking member proximally of the prosthesis passageway. The guidewire tracking member is adapted to track over a guidewire slideably received within the guidewire lumen through the proximal and distal guidewire ports, or alternatively to provide guidewire access to the second branch lumen at the bifurcation region through the guidewire lumen. Further to this aspect, the access device may also include both the guidewire tracking member and also a guidewire.
In another aspect of this mode, the expandable prosthesis is an endolumenal stent which is adapted to provide radial support to the body lumen wall when the expandable prosthesis is expanded from the radially collapsed condition to the radially expanded condition. The side port of the endolumenal stent aspect of this mode is formed by a gap between adjacent support members which form the stent""s tubular body. Further to this aspect, the stent may be self-expanding, in which case the expansion member is a radially confining sheath which is adjustable over the stent between a constraining position to a releasing position, or may be balloon expandable, in which case the expansion member is an expandable balloon.
The present invention also includes a method of engaging an expandable prosthesis within an interior surface of a body lumen wall at a bifurcation region of a body lumen. The expandable prosthesis used according to this method has a longitudinal axis, a length along the longitudinal axis, a prosthesis passageway which extends along the longitudinal axis, and a side port located along the length and through which the prosthesis passageway communicates externally of the expandable prosthesis.
One mode of this method according to the present invention includes engaging a distal end portion of a dilator within the prosthesis passageway and also within the side port of the expandable prosthesis while the expandable prosthesis is in a radially collapsed condition.
One aspect of this mode further includes positioning the expandable prosthesis within the bifurcation region such that the proximal end portion of the expandable prosthesis is located within the common branch lumen, the distal end portion of the expandable prosthesis is located within the first branch lumen, and the side port is aligned with the entrance zone to the second branch lumen.
A further aspect of this mode also includes: after positioning the expandable prosthesis within the bifurcation region, dilating the side port with the distal end portion of the dilator from the initial inner diameter to an expanded inner diameter which is larger than the initial inner diameter. One additional variation of this further aspect includes engaging a distal end portion of a guidewire within the prosthesis passageway, through the side port, and within at least the entrance zone of the second branch lumen before dilating the side port with the dilator. Still other variations of this further aspect include: dilating the side port before adjusting the expandable prosthesis from the radially collapsed condition to the radially expanded condition within the bifurcation; dilating the side port while adjusting the expandable prosthesis from the radially collapsed condition to the radially expanded condition; and dilating the side port after adjusting the expanded prosthesis from the radially collapsed condition to the radially expanded condition.
Another mode of the method according to the present invention includes positioning a distal end portion of an access device within the prosthesis passageway and also within the side port while the expandable prosthesis is in a radially collapsed condition. In one variation of the access device a guidewire is provided, in another variation a guidewire tracking member is provided, and in still another variation both a guidewire and a guidewire tracking member are provided.
One aspect of this mode further includes: after engaging the distal end portion of the access device within the prosthesis passageway and side port of the expandable prosthesis, positioning the expandable prosthesis within the bifurcation region while in the radially collapsed condition such that the proximal end portion of the expandable prosthesis is located within the common branch lumen, the distal end portion of the expandable prosthesis is located within the first branch lumen, and the side port is aligned with the entrance zone to the second branch lumen. Still a further aspect includes: after positioning the expandable prosthesis within the bifurcation region, adjusting the expandable prosthesis with the expansion member from the radially collapsed condition to the radially expanded condition such that the distal end portion circumferentially engages the first branch lumen and the proximal end portion circumferentially engages the common branch lumen.